Methods for improving multimodal polyethylene and films produced therefrom

ABSTRACT

A blown film composition including a first high density polyethylene component and a second high density polyethylene component, wherein the blown film contains a mixture of three or more discrete molecular weight distributions, and wherein the second high density polyethylene component has at least one more discrete molecular weight distribution than the first high density polyethylene component.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/965,783, filed on Aug. 13, 2013, which is a continuation of U.S.patent application Ser. No. 13/676,893, filed on Nov. 14, 2012, nowissued as U.S. Pat. No. 8,580,893, which claims priority from U.S.Provisional Patent Application No. 61/578,987, filed on Dec. 22, 2011.

FIELD

The present disclosure is generally related to polyolefins and methodsof making polyolefins. More specifically, the present disclosure isrelated to methods of making improved polyethylene films.

BACKGROUND

A polyolefin is a polymer produced from a simple olefin monomer, oralkene with the general formula C_(n)H_(2n). Polyolefins may be used inblown films. An example of a polyolefin is polyethylene, which isproduced by polymerizing the olefin ethylene. One type of polyethyleneis high density polyethylene, or HDPE. HDPE is defined by having adensity of greater or equal to 0.941 g/cm³. HDPE is commonly used in awide array of products and packaging including products such as milkjugs, laundry detergent bottles, plastic bags, garbage containers andtoys. HDPE blown films may include HDPE barrier films having moisturebarrier and/or vapor barrier properties.

Multiple challenges exist in producing HDPE barrier films. For example,obtaining a desired melt strength can be a difficulty with narrowmolecular weight resins, resins that lack long chain branching, andresins with high melt indices. Various methods have been tried toimprove these properties of barrier films.

SUMMARY

An embodiment of the present disclosure, either by itself or incombination with other embodiments, is a blown film composition thatincludes a first high density polyethylene component, a second highdensity polyethylene component and a nucleating agent, where the blownfilm composition is a combination of three or more discrete molecularweight distributions. The first high density polyethylene component canbe unimodal, have a density ranging from 0.950 to 0.970 g/cm³ and a meltflow index (MFI) ranging from 0.5 to 5.0 g/10 min and can be in amountsranging from 60 to 99 wt % based on the total weight of the blown filmcomposition. The second high density polyethylene component can bebimodal, have a density ranging from 0.945 to 0.970 g/cm³ and a MFIranging from 0.1 to 5.0 g/10 min.

The blown film composition can have a water vapor transmission rate(WVTR) at 2 mil of less than 0.130 g/100 in²/day at maximum frost lineheight. The WVTR at 2 mil can be less than the WVTR of either the firstor second high density polyethylene component absent the polyethylenecompatible nucleating agent

The blown film composition can have a decrease in haze of at least 10%and an increase in gloss of at least 10% over an identical blown filmcomposition absent the polyethylene compatible nucleating agent.Optionally the blown film composition can have a decrease in haze of atleast 20% and an increase in gloss of at least 40% at maximum frost lineheight over an identical blown film composition absent the polyethylenecompatible nucleating agent.

An embodiment of the disclosure can include an article made from theblown film composition.

An alternate embodiment, either by itself or in combination with otherembodiments, is a multimodal blend of a first high density polyethylenecomponent, a second high density polyethylene component and apolyethylene compatible nucleating agent where the blend is a mixture ofthree or more discrete molecular weight distributions. The weight ratioof the first high density polyethylene component to the second highdensity polyethylene component in the multimodal blend can be from 25:1to 3:1. The multimodal blend when blown to a film with maximum stablefrost line height can have a WVTR of less than 0.250 g/100 in²/day. Thefirst high density polyethylene component can be unimodal and the secondhigh density polyethylene component can be bimodal. The blend can have adecrease in haze of at least 10% and an increase in gloss of at least10% over an identical blend absent the polyethylene compatiblenucleating agent. An embodiment of the disclosure can include an articlemade from the blown film composition.

An alternate embodiment is a method of making a multimodal film thatincludes combining a first high density polyethylene component, a secondhigh density polyethylene component, and a polyethylene compatiblenucleating agent, to form a multimodal resin having three or morediscrete molecular weight distributions. The second high densitypolyethylene component has at least one more discrete molecular weightdistribution than the first high density polyethylene component.

Other possible embodiments include two or more of the above embodimentsof the disclosure. In an embodiment the method includes all of the aboveembodiments and the various procedures can be carried out in any order.

BRIEF DESCRIPTION OF DRAWINGS

The present disclosure is best understood from the following detaileddescription when read with the accompanying figures.

FIG. 1 is a graph of a molecular weight distribution of two polyethylenecomponents of an embodiment of a multimodal blend.

FIG. 2 is a graph of the water vapor transmission rates for severalmultimodal blend samples.

FIG. 3 is a graph of molecular weight distribution of a bimodalpolyethylene.

FIG. 4 is a graph molecular weight distribution molecular weightdistribution of a trimodal polyethylene blend.

FIG. 5 is a web graph of properties for several multimodal blendsamples.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of various embodiments.Specific examples of components and arrangements are described below tosimplify the present disclosure. These are, of course, merely examplesand are not intended to be limiting.

Disclosed herein are nucleators that are effective in a multimodalpolyethylene blend. Also disclosed herein is a nucleated multimodalpolyethylene blend having improved barrier properties over anon-nucleated multimodal polyethylene blend. Further disclosed is anucleated multimodal blend having a lower haze and a higher gloss whencompared to a non-nucleated blend, wherein frost height is maximized.Further disclosed herein are methods of making a nucleated multimodalpolyethylene blend.

The catalyst systems that may be useful in polymerizing olefin monomersinclude any suitable catalyst system. The catalysts used in conjunctionwith the present disclosure may include for example, chromium basedcatalyst systems, single site transition metal catalyst systemsincluding metallocene catalyst systems, Ziegler-Natta catalyst systemsor combinations thereof. The polymerization catalysts may be activatedand may or may not be associated with a support material. The followingdiscussion of such catalyst systems included below is in no way intendedto limit the scope of the present disclosure to such catalysts.

Ziegler-Natta catalyst systems may be formed from the combination of ametal component (e.g., a catalyst) with one or more additionalcomponents, such as a catalyst support, a cocatalyst and/or one or moreelectron donors. In some embodiments, the Ziegler-Natta catalyst systemsinclude magnesium-supported catalyst systems. In an embodiment, forexample, a magnesium-supported Ziegler-Natta catalyst may be prepared bythe steps of: preparing a metal dialkoxide as the reaction product of ametal dialkyl and an alcohol; followed by preparing a soluble catalystprecursor as the reaction product of the metal dialkoxide and ahalogenating/titanating agent; and lastly followed by precipitating of afinal solid catalyst component as the reaction product of the solublecatalyst precursor and a precipitating agent. The precipitating agentmay also be used as a halogenating/titanating agent. The process ofpreparing the Ziegler-Natta catalyst may include further steps, such asadditional halogenating/titanating steps.

The metal dialkyls may include Group IIA metal dialkyls. In a specificembodiment, the metal dialkyl is a magnesium dialkyl. The magnesiumdialkyl may be selected from the group of diethyl magnesium, dipropylmagnesium, dibutyl magnesium, and butylethyl magnesium (BEM) andcombinations thereof.

Metallocenes may include organometallic compounds containing twocyclopentadienyl rings bonded to a metal atom. Metallocene catalystsgenerally include a transition metal situated between to organic rings.Metallocene catalysts are homogenous (soluble in hydrocarbons), whereasZiegler-Natta catalysts are heterogeneous. Metallocene catalysts may becharacterized as coordination compounds incorporating one or morecyclopentadienyl (Cp) groups (which may be substituted or unsubstituted,each substitution being the same or different) coordinated with atransition metal through IC bonding. The substituent groups on the Cpgroups may be linear, branched or cyclic hydrocarbyl radicals. Thecyclic hydrocarbyl radicals may further form other contiguous ringstructures, including, but not limited to, indenyl, azulenyl andfluorenyl groups. These contiguous ring structures may furthersubstituted or unsubstituted by hydrocarbyl radicals, such as C₁ to C₂₀hydrocarbyl radicals.

Any desired polymerization process(es) may be carried out over thedesired polymerization catalyst(s). The equipment, process conditions,reactants, additives and any other materials that may be used in thepolymerization process(es) can vary depending on the desired compositionand properties of the polymer being formed. The polymerization processesmay include solution phase, gas phase, slurry phase, bulk phase, highpressure processes or any combinations thereof. (See, U.S. Pat. No.4,271,060, U.S. Pat. No. 5,001,205, U.S. Pat. No. 5,236,998 and U.S.Pat. No. 5,525,678, U.S. Pat. No. 5,589,555; U.S. Pat. No. 6,420,580;U.S. Pat. No. 6,380,328; U.S. Pat. No. 6,359,072; U.S. Pat. No.6,346,586; U.S. Pat. No. 6,340,730; U.S. Pat. No. 6,339,134; U.S. Pat.No. 6,300,436; U.S. Pat. No. 6,274,684; U.S. Pat. No. 6,271,323; U.S.Pat. No. 6,248,845; U.S. Pat. No. 6,245,868; U.S. Pat. No. 6,245,705;U.S. Pat. No. 6,242,545; U.S. Pat. No. 6,211,105; U.S. Pat. No.6,207,606; U.S. Pat. No. 6,180,735 and U.S. Pat. No. 6,147,173, each ofwhich are incorporated by reference herein in their entirety.)

Gas phase polymerization processes useful with the present disclosuremay include a continuous cycle system. A continuous cycle system mayinclude a cycling gas stream, which may include a recycle stream orother fluidizing medium, which is heated in a reactor by the heat ofpolymerization. The heat is then removed from the cycling gas stream bya cooling system external to the reactor. The cycling gas streamcontaining one or more monomers may be continuously cycled through afluidized bed in the presence of a catalyst under reactive conditions.The cycling gas stream may be withdrawn from the fluidized bed andrecycled back into the reactor. A polymer product may be simultaneouslywithdrawn from the reactor while fresh monomer may be added to replacethe polymerized monomer (polymer product). The gas phase process may beoperated under reactor pressures ranging from 100 to 500 psig, from 200to 400 psig, or from 250 to 350 psig. The gas phase process may beoperated under reaction temperatures ranging from 30 to 120° C., from 60to 115° C., from 70 to 110° C., or from 70 to 95° C. (See, for example,U.S. Pat. No. 4,543,399; U.S. Pat. No. 4,588,790; U.S. Pat. No.5,028,670; U.S. Pat. No. 5,317,036; U.S. Pat. No. 5,352,749; U.S. Pat.No. 5,405,922; U.S. Pat. No. 5,436,304; U.S. Pat. No. 5,456,471; U.S.Pat. No. 5,462,999; U.S. Pat. No. 5,616,661; U.S. Pat. No. 5,627,242;U.S. Pat. No. 5,665,818; U.S. Pat. No. 5,677,375 and U.S. Pat. No.5,668,228, each of which are incorporated by reference herein in theirentirety.)

Slurry phase processes may include forming a suspension of solid,particulate polymer in a liquid polymerization medium, and addingmonomers, catalyst and optionally hydrogen to the medium. The suspensionmay be intermittently or continuously removed from the reactor. Theremoved suspension may then be subjected to separation step where thevolatile components can be separated from the polymer and recycled tothe reactor. The suspension may further include a diluent, such as a C₃to C₇ alkane (e.g., hexane or isobutene), which is generally liquidunder the conditions of polymerization and relatively inert. A bulkphase process is similar to that of a slurry process, except that in thebulk phase process the liquid medium is also the reactant (e.g.,monomer). In an embodiment, the polymerization process may be a bulkprocess, a slurry process or a bulk slurry process.

In an embodiment, a slurry process or a bulk process may be carried outcontinuously in one or more loop reactors. The catalyst, as slurry or asa dry free flowing powder, may be injected intermittently orcontinuously into the reactor loop. In an alternative embodiment,hydrogen may be added to the process in order to aid in molecular weightcontrol of the resultant polymer. The loop reactor may be operated underpressures ranging from 27 to 50 bar or from 35 to 45 bar and undertemperatures ranging from 38 to 121° C. In an embodiment, reaction heatmay be removed through the wall of the loop reactor by any suitablemethod, such as by a double-jacketed pipe or heat exchanger.

In an embodiment, the slurry polymerization process may be carried outin a stirred reactor, such as a continuously stirred tank reactor(CSTR). Other types of polymerization processes may be used, such asstirred reactors in series, parallel or combinations thereof. Uponleaving the reactor, the polymer may be subjected to further processing,such as addition of additives and/or extrusion.

The polymers, including blends thereof, formed via the processesdescribed herein may include, but are not limited to, high densitypolyethylene (HDPE), medium density polyethylene (MDPE), low densitypolyethylene (LDPE), linear low density polyethylene (LLDPE), and verylow density polyethylene (VLDPE) for example.

The blend of the present disclosure may include at least twoethylene-based polymeric components. In certain embodiments, the blendcontains only ethylene-based polymeric components. In an embodiment, theblend of the present disclosure includes at least one ethylenehomopolymer component. In another embodiment, the blend of the presentdisclosure includes at least one ethylene homopolymer and at least oneother ethylene homopolymer or copolymer, and combinations andmodifications thereof. In a further embodiment, the blend of the presentdisclosure is a multimodal polyethylene composition. In certainembodiments, the blend contains only a multi-modal polyethylenecomposition, i.e., no other polymeric components. As referred to herein,the term “multimodal” refers to a mixture of two or more discretemolecular weight distributions, or “modes”.

In an embodiment, the multimodal composition includes at least twocomponents. In an embodiment, the at least two components each includeat least one discrete molecular weight distribution, or mode. In anotherembodiment, the at least two components of the multimodal compositioninclude a first component and a second component. In an embodiment, thefirst component has at least one mode and the second component has atleast two modes. In an embodiment, the second high density polyethylenecomponent has at least one more discrete molecular weight distributionthan the first high density polyethylene component. In a specificembodiment, the multimodal polyethylene composition includes a unimodalcomponent and a bimodal component, resulting in a trimodal composition.In an embodiment either component may have more than one mode which whenthe components are combined yields a molecular weight distribution (MWD)of from 2.0 to 25.

The first component of the multimodal composition may include apolyethylene homopolymer. In an embodiment, the first component may havedensities ranging from 0.880 to 0.970 g/cm³, which encompasses what arereferred to as low density, medium density and high densitypolyethylene. High density polyethylene (HDPE) typically has densityranging from 0.941 to 0.970 g/cm³, medium density polyethylene (MDPE)has density ranging from 0.926 to 0.940 g/cm³, linear low densitypolyethylene (LLDPE) has density ranging from 0.916 to 0.925 g/cm³ andvery low density polyethylene (VLDPE) resins typically have densitiesfrom 0.890 to 0.915 g/cm³. In an embodiment, the density of the firstcomponent ranges from 0.950 to 0.970 g/cm³, optionally from 0.960 to0.965 g/cm³, or optionally from 0.961 to 0.963 g/cm³. The densities ofthe polyethylene components may be determined in accordance with ASTM D792.

In an embodiment the first component of the multimodal composition mayhave a MFI of at least 0.1 g/10 min. In another embodiment, the firstcomponent has a MFI ranging from 0.1 to 5.0 g/10 min, optionally from1.0 to 3.0 g/10 min, optionally from 1.5 to 2.5 g/10 min. The melt flowindex of the polyethylene can be measured using the procedures of ASTM D1238 at 190° C. using a load of 2.16 kg.

In an embodiment, the molecular weight of the first component rangesfrom 1,000 g/mol to 10,000,000 g/mol. In another embodiment, themolecular weight of the first component ranges from 3,000 g/mol to500,000 g/mol, optionally from 10,000 to 200,000 g/mol, optionally from30,000 to 100,000 g/mol. In an embodiment, the molecular weightdistribution (MWD) of the first component ranges from 2 to 25,optionally 4 to 18, and optionally 5 to 12.

When measured on two mil films, the first component may possess anElmendorf Tear strength (measured using the ASTM test method D 1922) inthe machine direction (MD) ranging from 10 to 50 g, optionally 20 to 30g, and optionally 22 to 26 g, and in the transverse direction (TD)ranging from 200 to 600 g, optionally 300 to 500 g, and optionally 375to 400 g. The tensile strength (measured using the ASTM test method D882A at 20 in/min) of the first component at yield may range from 1000to 6000 psi, optionally 3000 to 5000 psi, and optionally 3500 to 4100 inthe MD and may range from 1000 to 6000 psi, optionally 3000 to 5000, andoptionally 3700 to 4300 in the TD and at break may range from 5000 to10000, optionally from 6000 to 9000, and optionally from 7000 to 8000 inthe MD and may range from 2000 to 5000, optionally 2500 to 4500, andoptionally 3300 to 3500 in the TD. The elongation at break in both theMD and the TD (measured using ASTM test method D 882A at 20 in/min) ofthe first component may range from 100 to 1000%, optionally 400 to 900%,and optionally 600 to 800%. The secant modulus at 1% strain (measuredusing ASTM test method D 882A at 20 in/min) of the first component inthe MD may range from 50 to 200 kpsi, optionally 100 to 150 kpsi, andoptionally 120 to 130 kpsi and in the TD may range from 50 to 200 kpsi,optionally 100 to 150 kpsi, and optionally 124 to 132 kpsi. The secantmodulus at 2% strain (measured using ASTM test method D 882A at 1in/min) of the first component in the MD may range from 50 to 200 kpsi,optionally 75 to 125 kpsi, and optionally 95 to 105 kpsi and in the TDmay range from 50 to 200 kpsi, optionally 75 to 125 kpsi, and optionally98 to 106 kpsi.

The first component may possess a water vapor transmission rate (WVTR)(measured at 100° F. using ASTM test method E96/66) ranging from 0.01 to0.5 g/100 in²/day, optionally ranging from 0.1 to 0.4 g/100 in²/day, andoptionally ranging from 0.2 to 0.3 g/100 in²/day. The first componentmay be for example, HDPE 6420, commercially available from TotalPetrochemicals USA, Inc.

The second component of the multimodal composition may also include apolyethylene homopolymer, copolymer, and any combinations andmodifications thereof. In an embodiment the second component may havedensities ranging from 0.880 to 0.970 g/cm³, which encompasses what arereferred to as low density, medium density and high densitypolyethylene. In an embodiment, the density of the second componentranges from 0.940 to 0.970 g/cm³, optionally from 0.950 to 0.965 g/cm³,optionally from 0.952 to 0.962 g/cm³, optionally from 0.956 to 0.960g/cm³. The densities of the polyethylene components may be determined inaccordance with ASTM D 792.

In another embodiment the second component of the multimodal compositionmay have a melt flow index (MFI) ranging from 0.1 to 5.0 g/10 min. Inanother embodiment, the second component has a MFI ranging from 0.1 to2.0 g/10 min. In an alternative embodiment, the second component has aMFI ranging from 0.2 to 1.0 g/10 min. In a further embodiment, thesecond component has a MFI ranging from 0.3 to 0.6 g/10 min. The meltflow index of the polyethylene second component is measured using theprocedures of ASTM D 1238 at 190° C. using a load of 2.16 kg.

In an embodiment, the molecular weight of the second component rangesfrom 1,000 g/mol to 10,000,000 g/mol. In another embodiment, themolecular weight of the second component ranges from 1,000 g/mol to1,000,000 g/mol. In a further embodiment, the molecular weight of thesecond component ranges from 2,000 to 300,000 g/mol. In an even furtherembodiment, the molecular weight of the second component ranges from20,000 to 100,000 g/mol. In an embodiment, the molecular weightdistribution (MWD) of the second component ranges from 2 to 25,optionally 4 to 18, and optionally 5 to 12.

The second component may posses a dart impact (measured using ASTM testmethod D 1709A) of less than 100 g, optionally less than 75 g, andoptionally less than 50 g. Measured on two mil films, the secondcomponent may possess an Elmendorf Tear strength (measured using theASTM test method D 1922) in the machine direction (MD) ranging from 1 to30 g, optionally 10 to 20 g, and optionally 13 to 17 g, and in thetransverse direction (TD) ranging from 100 to 10000 g, optionally 500 to2000 g, and optionally 1000 to 1100 g. The tensile strength (measuredusing the ASTM test method D 882A at 20 in/min) of the second componentat yield may range from 1000 to 6000 psi, optionally 3500 to 5500 psi,and optionally 4400 to 4600 in the MD and may range from 1000 to 4000psi, optionally 2000 to 3000, and optionally 2500 to 2700 in the TD andat break may range from 5000 to 10000, optionally from 6000 to 9000, andoptionally from 7500 to 8000 in the MD and may range from 1000 to 4000,optionally 2000 to 3000, and optionally 2500 to 2700 in the TD. Theelongation at break (measured using ASTM test method D 882A at 20in/min) of the second component may range from 100 to 500%, optionally200 to 300%, and optionally 250 to 290% in the MD and may be less than100%, optionally less than 50%, and optionally less than 10% in the TD.The secant modulus at 1% strain (measured using ASTM test method D 882Aat 20 in/min) of the second component in the MD may range from 50 to 250kpsi, optionally 125 to 175 kpsi, and optionally 150 to 155 kpsi and inthe TD may range from 100 to 300 kpsi, optionally 150 to 250 kpsi, andoptionally 195 to 205 kpsi.

The second component may possess a water vapor transmission rate (WVTR)(measured at 100° F. using ASTM test method E96/66) ranging from 0.1 to2.0 g/100 in²/day, optionally ranging from 0.3 to 1.0 g/100 in²/day, andoptionally ranging from 0.6 to 0.8 g/100 in²/day. The second componentmay be for example, HDPE 9458, commercially available from TotalPetrochemicals USA, Inc.

The multimodal polyethylene blend of the present disclosure may includea nucleated material. In an embodiment, the nucleated material ispresent in the first composition, the second composition or combinationsthereof. In an embodiment, the nucleated material is obtained by the useof a nucleating agent. The nucleating agent refers to a foreign phase,or nucleation site, that when introduced into the material presents anew surface on which crystal growth can occur.

Nucleation of homophasic polymers may generally improve the opticalproperties, such as haze and clarity, of a polymer. However, nucleationof heterophasic polymers has not generally resulted in such improvedoptical properties.

The present disclosure, however, includes a polyethylene compatiblenucleator. Polyethylene compatible nucleators may include a nucleator,or nucleating agent, capable of accelerating phase change in ethylenebased polymers. The polyethylene compatible nucleator provides forpolymer blends exhibiting significantly improved optical properties. Inan embodiment, the polymer blends show a decrease in haze of at leastabout 10%, at least about 20% or at least about 30% over identicalpolymer blends absent the polyethylene compatible nucleator.

The nucleated material may be obtained by the introduction of anucleating agent into the multimodal blend by any desired means. Thenucleating agent may also be introduced at any point in the productionof the multimodal blend. In an embodiment, the nucleating agent may beintroduced at any point in the production of the first and/or secondcomponent. In an alternative embodiment, the nucleating agent isintroduced with the monomer feed of the first composition prior topolymerization of the first component. In another embodiment, thenucleating agent is introduced during the first componentpolymerization. In yet another embodiment, the nucleating agent iscombined with the first component at any point following thepolymerization of the first component.

In an embodiment, the nucleating agent is combined with the firstcomponent at any point following the polymerization of the firstcomponent but prior to the addition of the second component with thefirst component. In an embodiment, the nucleating agent is combined withthe first component via melt mixing of the nucleating agent with thefirst component in a molten, or liquid, state. In another embodiment,the nucleating agent is combined with the first component via the use ofa masterbatch, wherein the term “masterbatch” refers to the process offirst melt mixing the nucleator agent with a small amount of firstcomponent resin resulting in a masterbatch, followed by mixing themasterbatch with the remaining bulk of the first component resin. In afurther embodiment, via physical blending of the nucleating agent withthe first component in a solid, or solid-like, state.

In an embodiment, the nucleation may be performed by the methodsdescribed in U.S. Pat. Nos. 6,599,971, 6,794,433, and 7,332,536, each toDotson et al. and incorporated by reference herein in their entirety. Inan embodiment, the nucleation may be performed by the methods describedin U.S. Patent Application Nos. 20060047078 to Swabey et al. and20080118749 and 20090029182, to Aubee et al., and incorporated byreference herein in their entirety.

The nucleating agents may include any additive that presents a newsurface on which crystal growth can occur. The nucleating agents may beinorganic or organic. The inorganic nucleating agents may include smallparticulates such as talc and calcium carbonate. The nucleating agentsmay be selected from any polyethylene compatible nucleator known in theart. The polyethylene compatible nucleators maybe selected from thegroup of carboxylic acid salts, such as sodium benzoate, talc,phosphates, metallic-silicate hydrates, organic derivatives ofdibenzylidene sorbitol, sorbitol acetals, and organophosphate salts, andcombinations thereof. In an embodiment, the nucleating agents includeNa-11 (Sodium 2,2-methylene-bis-(4,6-di tert butylphenyl)phosphate) andNa-21 (primary component-Aluminum,hydroxybis[2,4,8,10-tetrakis(1,1-dimethylethyl)-6-hydroxy-12H-dibenzoi[d,g][1,3,2]dioxaphoshocin6-oxidato]), both commercially available from Amfine Chemical. In anoptional embodiment, the nucleating agents include Hyperform® HPN-68L(80% Bicyclo[2,2,1]Heptane-2,3-dicarboxylic acid, disodium salt+10%13-Docosenamide (Z)+10% Amorphous Silicon Dioxide), HPN-20E (34% ZincStearate+66% 1,2-Cyclohexanedicarboxylic Acid, Calcium salt), Millad3988 (3,4-dimethylebenzylidene sorbitol), and Millad 3940 ((1,3:2,4)Diparamethyldibenylidene sorbitol), each commercially available fromMilliken and Company. In a specific embodiment, the nucleating agentincludes Hyperform HPN-20E. In another embodiment, the nucleating agentsinclude HHPA salts (salts of dicarboxylic acids having ahexahydrophtalic acid structure).

The nucleating agents may be present in the multimodal blend in anyeffective amounts. In an embodiment, the nucleating agents are presentonly in the first component. In an embodiment, the nucleating agentspresent in the first component are present in amounts of at least 1 ppmby weight of the first component. In another embodiment, the nucleatingagents present in the first component are present in amounts rangingfrom 1 to 10,000 ppm by weight of the first component. In a furtherembodiment, the nucleating agents present in the first component arepresent in amounts ranging from 50 to 3,000 ppm. In an even furtherembodiment, the nucleating agents present in the first component arepresent in amounts ranging from 100 to 1,000 ppm.

The multimodal blend of the present disclosure may contain any suitableamounts of the first and/or second component. In an embodiment, thefirst component is present in the multimodal blend in amounts of atleast 50 wt % based on the total weight of the blend. In anotherembodiment, the first component is present in the multimodal blend inamounts ranging from 60 to 99 wt % based on the total weight of theblend. In a further embodiment, the first component is present in themultimodal blend in amounts ranging from 70 to 95 wt %. In an evenfurther embodiment, the first component is present in the multimodalblend in amounts ranging from 75 to 85 wt %.

In an embodiment, the second component is present in the multimodalblend in amounts of at least 0.1 wt % based on the total weight of theblend. In another embodiment, the first component is present in themultimodal blend in amounts ranging from 1 to 40 wt % based on the totalweight of the blend. In a further embodiment, the first component ispresent in the multimodal blend in amounts ranging from 5 to 30 wt %. Inan even further embodiment, the first component is present in themultimodal blend in amounts ranging from 15 to 25 wt %.

The first and second component may be present in the multimodal blend inany desired ratio. In an embodiment, the weight ratio of the firstcomponent to the second component in the multimodal blend is from 100:1to 1:1. In another embodiment, the weight ratio of the first componentto the second component in the multimodal blend is from 50:1 to 2:1. Ina further embodiment, the weight ratio of the first component to thesecond component in the multimodal blend is from 20:1 to 3:1. In an evenfurther embodiment, the weight ratio of the first component to thesecond component in the multimodal blend is from 10:1 to 3:1.

The multimodal blend of the present disclosure may also contain otheradditives. In an embodiment, these additives include antioxidants, fireretardants, lubricants, blowing agents, UV stabilizers, antistaticagents, and the like. Any additive known to those of ordinary skill inthe art to be useful in the preparation of polyethylene films may beused.

The multimodal blends of the present disclosure have demonstratedimprovements in frost line height, and consequently bubble stability.Frost line height refers to the distance from the die face wheresolidification of the molten resin occurs. The maximum frost line heightrefers to the maximum height the blown film could tolerate beforeencountering problems

The multimodal blends of the present disclosure may have improvedmoisture barrier properties. In an embodiment, at max frost line height,the films of the present disclosure have a water vapor transmission rate(WVTR) of less than 0.250 g/100 in²/day, optionally less than 0.240g/100 in²/day, optionally less than 0.220 g/100 in²/day, optionally lessthan 0.20 g/100 in²/day. In another embodiment, at max frost lineheight, the films of the present disclosure have a WVTR of less than 0.2g/100 in²/day. In a further embodiment, at max frost line height, thefilms of the present disclosure have a WVTR ranging from 0.1 to 0.3g/100 in²/day.

At a low frost line height, the films of the present disclosure may havea WVTR of at least 0.1 g/100 in²/day. In another embodiment, at a lowfrost line height, the films of the present disclosure have a WVTR ofless than 0.4 g/100 in²/day. In a further embodiment, at a low frostline height, the films of the present disclosure have a WVTR rangingfrom 0.2 to 0.3 g/100 in²/day. As used herein the term “low frost lineheight” refers to operating having a frost line height of less than 3die diameters in height. This is sometimes referred to in the art as“running in the pocket” or running with “no neck”.

In an embodiment, the gloss 45° of the multimodal blend at max frostline height is at least 50% of the gloss 45° of the multimodal blend ata low frost line height. In another embodiment, the gloss 45° of themultimodal blend at max frost line height is at least 70% of the gloss45° of the multimodal blend at a low frost line height. In anembodiment, the haze of the multimodal blend at a low frost line heightis at least 50% of the haze of the multimodal blend at max frost lineheight. In an embodiment, the haze of the multimodal blend at a lowfrost line height is at least 70% of the haze of the multimodal blend atmax frost line height. As used herein, the term “frost line height”refers to the point after the die at which phase change of the melt tothe crystalline state occurs. In an embodiment, the max frost lineheight is at least 3 die diameters. In an embodiment, the low frost lineheight is from 2 to 3 die diameters.

In an embodiment, the multimodal blends of the present disclosure may beprepared by physical blending the first component and the secondcomponent. In another embodiment, the multimodal blends are preparedin-situ. In one process, a single reactor is employed with two or moredistinctly different catalysts, wherein each catalyst is preparedseparately on its respective support and can produce a distinctmolecular weight product than the other catalyst(s). In this in-situprocess, two or more distinctly different polymers are created, and themultimodal product is heterogenous.

In a second in-situ process, a single reactor is again used, however twoor more different catalysts are contained on the same support. Multipledifferent polymers may be produced from the same catalyst particle,resulting in a polymer described as “interstitially mixed.” Such anin-situ process, therefore, may achieve a much greater degree ofhomogeneity in the polymer product than the previously described in-situprocess.

In an embodiment, the multimodal blend may be prepared in accordancewith procedures disclosed in U.S. Pat. Nos. 7,396,892 and 7,473,745 toMcGrath and Chandrashekar et al., respectively, each incorporated byreference herein in their entirety.

In another embodiment, the multimodal blend of the present disclosuremay be prepared in at least two polymerization reactors in a seriesand/or parallel arrangement. In a further embodiment, the multimodalblend of the present disclosure may be prepared by polymerizing at leastone mode of the multimodal blend in a first reactor followed by thepolymerization of another mode in a subsequent reactor in series. In aneven further embodiment, the multimodal blend of the present disclosuremay be prepared by a cascade arrangement of at least two polymerizationreactors in series in which each polymerization reactor is operatedunder different conditions resulting in a multimodal or bimodal reactionproduct. The polymerization reactors may be plug flow reactors,continuous stirred tank reactors (CSTR), or any combinations thereof.

The polymers and blends thereof of the present disclosure may be usefulin applications known to one skilled in the art, including formingoperations (e g, film, sheet, pipe and fiber extrusion and co-extrusionas well as blow molding, injection molding and rotary molding). Filmsinclude blown, oriented, or cast films formed by extrusion,co-extrusion, or by lamination. Useful films are those such as shrinkfilms, cling films, stretch films, sealing films, heavy-duty bags,grocery sacks, food packaging, medical packaging, commercial packaging,industrial liners, and membranes. Fibers include slit-films,monofilaments, melt spinning, solution spinning and melt blown fiber.Useful fibers are those such as woven or non-woven fibers that may beused to make sacks, bags, rope, twine, carpet backing, carpet yarns,filters, diaper fabrics, medical garments and geotextiles. Extrudedarticles include medical tubing, wire and cable coatings, and sheets,such as thermoformed sheets (e.g., plastic corrugated cardboard),geomembranes and pond liners. Molded articles include single andmulti-layered constructions in the form of bottles, tanks, drums, largehollow articles, rigid food containers and toys.

In an embodiment, the polymers and blends thereof are used to formfilms. In another embodiment, the polymers and blends thereof are usedto form blown films.

EXAMPLES

As used herein, Polymer “A” is Total 6420, which is commerciallyavailable from Total Petrochemicals USA, Inc. and is a HDPE having adensity of 0.962 g/cm³ and an MFI of 2.0 g/10 min.

As used herein, Polymer “B” is Total 9458, which is commerciallyavailable from Total Petrochemicals USA, Inc. and is a bimodal HDPEhaving a density of 0.958 g/cm³ and an MFI of 0.45 g/10 min.

As used herein, Polymer “C” is a nucleated version of Total 6420, whichis commercially available from Total Petrochemicals USA, Inc. and is aHDPE having a density of 0.962 g/cm³ and an MFI of 2.0 g/10 min that hasbeen subjected to a nucleating agent Hyperform® HPN-20E in amount of1500 ppm per weight of 6420.

Example 1

A multimodal composition was obtained through physical blending a firstpolyethylene component and a second polyethylene component. Total 6420,or Polymer “A”, commercially available from Total Petrochemicals USA,Inc., was used as the first component or unimodal portion and Total9458, or Polymer “B”, commercially available from Total PetrochemicalsUSA, Inc., was used as the second component or bimodal portion, and ascombined they created a trimodal melt blend. The nucleated version of6420 may be referred to herein as Polymer “C”. The gel permeationchromatography of each polyethylene component is depicted in FIG. 1.Although polymer B may appear to have a single broad MWD in FIG. 1, itis a bimodal PE product wherein the overlap of the two modes results ina combined MWD as shown, the two modes and the combined mode is shown inFIG. 3. The results of this experiment show that the combination of thefirst and second component created synergistic results in the blendsuperior to using either component alone or separately. The modes of thecombination of the first and second component are shown in FIG. 4 and intable form in Table 2.

The processing benefits of using the blend are demonstrated in theunnucleated blends. As the amount of “B” added to “A” was increased from0 to 20 wt %, the ability to increase frostline height rose. Addingbimodal HDPE, 9458 (“B”), to “A” also incrementally lowers motoramperes. The processing data for these results are shown in Table 1.

TABLE 1 Processing Data Maximum Frost Line Height Extruder Melt PressureMaterial (Die Diameters) Amps (psi) A 13 51 2812 95%-A/5%-B 17 51 279390%-A/10%-B 20 50 2820 80%-A/20%-B 23 49 2912 C 51 2727 95%-C/5%-B 472692 90%-C/10%-B 47 2698 80%-C/20%-B 48 2814

TABLE 2 Molecular Weight Distribution of Trimodal Blend 6420/9458 Low MWHigh MW (80/20%) Fraction Fraction 6420 Fraction Reconstituted % Area MW% Area MW % Area MW % Area MW % Area MW 0.006 5,226,722 0.003 1,870,4170.002 4,322,458 0.026 3,076,641 0.002 4,322,458 0.010 4,793,071 0.0031,723,869 0.003 3,967,693 0.028 2,828,914 0.003 3,967,693 0.0134,397,361 0.003 1,589,392 0.005 3,643,622 0.033 2,602,196 0.0053,643,622 0.015 4,036,096 0.004 1,465,940 0.007 3,347,448 0.0382,394,609 0.007 3,347,448 0.017 3,706,119 0.005 1,352,561 0.0103,076,641 0.043 2,204,454 0.036 3,076,641 0.020 3,404,576 0.0061,248,392 0.013 2,828,914 0.050 2,030,189 0.042 2,828,914 0.0253,128,886 0.007 1,152,643 0.017 2,602,196 0.060 1,870,417 0.0502,602,196 0.031 2,876,716 0.008 1,064,601 0.021 2,394,609 0.0691,723,869 0.059 2,394,609 0.038 2,645,951 0.009 983,611 0.026 2,204,4540.079 1,589,392 0.069 2,204,454 0.047 2,434,680 0.009 909,080 0.0302,030,189 0.089 1,465,940 0.081 2,030,189 0.056 2,241,166 0.010 840,4670.034 1,870,417 0.099 1,352,561 0.097 1,870,417 0.067 2,063,840 0.011777,278 0.037 1,723,869 0.108 1,248,392 0.109 1,723,869 0.080 1,901,2750.012 719,061 0.042 1,589,392 0.116 1,152,643 0.124 1,589,392 0.0951,752,178 0.013 665,406 0.046 1,465,940 0.124 1,064,601 0.139 1,465,9400.112 1,615,373 0.014 615,937 0.050 1,352,561 0.132 983,611 0.1541,352,561 0.128 1,489,795 0.015 570,312 0.053 1,248,392 0.141 909,0800.168 1,248,392 0.145 1,374,474 0.016 528,216 0.058 1,152,643 0.151840,467 0.181 1,152,643 0.162 1,268,528 0.016 489,364 0.063 1,064,6010.163 777,278 0.195 1,064,601 0.179 1,171,155 0.016 453,492 0.068983,611 0.176 719,061 0.209 983,611 0.197 1,081,625 0.017 420,362 0.074909,080 0.192 665,406 0.224 909,080 0.215 999,274 0.019 389,753 0.079840,467 0.211 615,937 0.240 840,467 0.234 923,497 0.020 361,465 0.084777,278 0.231 570,312 0.259 777,278 0.254 853,741 0.021 335,312 0.090719,061 0.254 528,216 0.278 719,061 0.277 789,504 0.021 311,127 0.096665,406 0.279 489,364 0.301 665,406 0.301 730,327 0.023 288,754 0.103615,937 0.308 453,492 0.327 615,937 0.327 675,790 0.025 268,051 0.109570,312 0.341 420,362 0.355 570,312 0.356 625,513 0.027 248,887 0.116528,216 0.377 389,753 0.385 528,216 0.387 579,145 0.029 231,144 0.123489,364 0.416 361,465 0.418 489,364 0.421 536,367 0.031 214,710 0.131453,492 0.459 335,312 0.455 453,492 0.459 496,888 0.034 199,486 0.138420,362 0.505 311,127 0.496 420,362 0.500 460,440 0.037 185,378 0.144389,753 0.555 288,754 0.540 389,753 0.543 426,780 0.040 172,300 0.151361,465 0.609 268,051 0.588 361,465 0.588 395,683 0.044 160,175 0.159335,312 0.667 248,887 0.639 335,312 0.638 366,946 0.049 148,929 0.168311,127 0.729 231,144 0.694 311,127 0.693 340,380 0.054 138,497 0.174288,754 0.793 214,710 0.752 288,754 0.750 315,814 0.060 128,818 0.180268,051 0.860 199,486 0.815 268,051 0.810 293,090 0.066 119,834 0.187248,887 0.929 185,378 0.881 248,887 0.874 272,064 0.073 111,493 0.193231,144 0.999 172,300 0.951 231,144 0.942 252,603 0.079 103,749 0.199214,710 1.072 160,175 1.023 214,710 1.009 234,584 0.087 96,556 0.203199,486 1.147 148,929 1.097 199,486 1.079 217,897 0.095 89,874 0.208185,378 1.224 138,497 1.173 185,378 1.153 202,439 0.103 83,666 0.211172,300 1.302 128,818 1.251 172,300 1.232 188,114 0.111 77,895 0.215160,175 1.379 119,834 1.331 160,175 1.311 174,837 0.120 72,532 0.217148,929 1.454 111,493 1.413 148,929 1.390 162,527 0.128 67,545 0.219138,497 1.526 103,749 1.498 138,497 1.469 151,111 0.137 62,907 0.220128,818 1.594 96,556 1.582 128,818 1.550 140,522 0.145 58,594 0.220119,834 1.656 89,874 1.665 119,834 1.632 130,696 0.154 54,582 0.220111,493 1.711 83,666 1.746 111,493 1.713 121,577 0.162 50,848 0.219103,749 1.757 77,895 1.824 103,749 1.791 113,112 0.171 47,374 0.21896,556 1.791 72,532 1.898 96,556 1.867 105,252 0.180 44,140 0.214 89,8741.815 67,545 1.965 89,874 1.933 97,953 0.188 41,130 0.209 83,666 1.83062,907 2.023 83,666 1.992 91,172 0.195 38,328 0.204 77,895 1.836 58,5942.072 77,895 2.045 84,871 0.202 35,718 0.197 72,532 1.834 54,582 2.10872,532 2.089 79,016 0.208 33,288 0.189 67,545 1.827 50,848 2.132 67,5452.119 73,573 0.215 31,025 0.179 62,907 1.817 47,374 2.146 62,907 2.13768,513 0.220 28,916 0.170 58,594 1.802 44,140 2.150 58,594 2.146 63,8080.225 26,952 0.159 54,582 1.781 41,130 2.146 54,582 2.149 59,432 0.23025,121 0.149 50,848 1.756 38,328 2.138 50,848 2.147 55,361 0.234 23,4160.138 47,374 1.726 35,718 2.126 47,374 2.141 51,574 0.237 21,826 0.12844,140 1.690 33,288 2.109 44,140 2.129 48,049 0.239 20,344 0.118 41,1301.650 31,025 2.087 41,130 2.112 44,769 0.240 18,963 0.109 38,328 1.60628,916 2.060 38,328 2.088 41,715 0.240 17,676 0.101 35,718 1.560 26,9522.028 35,718 2.059 38,873 0.241 16,476 0.092 33,288 1.510 25,121 1.99133,288 2.023 36,226 0.241 15,357 0.083 31,025 1.458 23,416 1.948 31,0251.981 33,760 0.240 14,313 0.075 28,916 1.404 21,826 1.901 28,916 1.93131,465 0.239 13,341 0.066 26,952 1.349 20,344 1.852 26,952 1.878 29,3260.236 12,433 0.059 25,121 1.293 18,963 1.799 25,121 1.823 27,333 0.23311,587 0.052 23,416 1.237 17,676 1.744 23,416 1.767 25,477 0.230 10,7980.045 21,826 1.181 16,476 1.686 21,826 1.710 23,747 0.227 10,062 0.03920,344 1.124 15,357 1.627 20,344 1.651 22,135 0.223 9,376 0.034 18,9631.068 14,313 1.567 18,963 1.591 20,632 0.219 8,736 0.029 17,676 1.01413,341 1.506 17,676 1.530 19,232 0.214 8,139 0.024 16,476 0.962 12,4331.445 16,476 1.471 17,926 0.208 7,582 0.019 15,357 0.912 11,587 1.38415,357 1.409 16,709 0.203 7,063 0.015 14,313 0.863 10,798 1.324 14,3131.347 15,574 0.198 6,579 0.012 13,341 0.815 10,062 1.265 13,341 1.28414,516 0.192 6,127 0.010 12,433 0.769 9,376 1.208 12,433 1.225 13,5300.186 5,705 0.008 11,587 0.725 8,736 1.153 11,587 1.167 12,610 0.1805,312 0.006 10,798 0.681 8,139 1.100 10,798 1.109 11,752 0.174 4,9460.005 10,062 0.639 7,582 1.046 10,062 1.054 10,952 0.168 4,604 0.0039,376 0.601 7,063 0.995 9,376 1.002 10,206 0.162 4,286 0.003 8,736 0.5646,579 0.946 8,736 0.951 9,510 0.155 3,988 0.002 8,139 0.529 6,127 0.8988,139 0.902 8,861 0.149 3,711 0.003 7,582 0.495 5,705 0.850 7,582 0.8558,255 0.142 3,453 0.003 7,063 0.464 5,312 0.806 7,063 0.811 7,691 0.1363,212 0.002 6,579 0.434 4,946 0.764 6,579 0.768 7,164 0.129 2,987 0.4064,604 0.721 6,127 0.724 6,673 0.123 2,778 0.379 4,286 0.682 5,705 0.6816,215 0.117 2,583 0.353 3,988 0.644 5,312 0.641 5,787 0.111 2,401 0.3293,711 0.609 4,946 0.604 5,389 0.105 2,232 0.306 3,453 0.574 4,604 0.5695,017 0.098 2,074 0.285 3,212 0.540 4,286 0.536 4,671 0.092 1,927 0.2652,987 0.508 3,988 0.503 4,347 0.086 1,790 0.246 2,778 0.478 3,711 0.4724,046 0.081 1,662 0.228 2,583 0.449 3,453 0.442 3,765 0.076 1,543 0.2112,401 0.421 3,212 0.416 3,503 0.070 1,432 0.195 2,232 0.394 2,987 0.3913,259 0.064 1,329 0.181 2,074 0.369 2,778 0.365 3,031 0.059 1,233 0.1681,927 0.345 2,583 0.339 2,819 0.156 1,790 0.321 2,401 0.315 2,621 0.1421,662 0.300 2,232 0.293 2,436 0.128 1,543 0.279 2,074 0.271 2,265 0.1141,432 0.260 1,927 0.251 2,104 0.101 1,329 0.243 1,790 0.232 1,955 0.0891,233 0.223 1,662 0.214 1,816 0.079 1,144 0.204 1,543 0.198 1,687 0.1841,432 0.182 1,566 0.166 1,329 0.169 1,454 0.148 1,233 0.156 1,349 0.1431,252 0.129 1,161

Example 2

Films with a thickness of 2 mil were produced at two different frostline heights from the polymers and blends of Example 1. The minimumfrost line height (FLH) was held constant at 5.5″ (2.30 die diameters).The maximum frost line height was varied according to what the blownfilm could tolerate before encountering instability or other processingproblems. These 2 mil films were then tested for barrier properties, aslisted in Table 3 and shown in FIG. 2.

TABLE 3 Barrier Properties of the Materials Tested 2 mil film WVTRnormalized WVTR (g/100 in²/day) (g/100 in²/day) @ Max. @ Low @ Max. @Low Material FLH FLH FLH FLH A 0.122 0.138 0.244 0.276 B 0.188 0.2350.376 0.470 95%-A/5%-B 0.077 0.103 0.154 0.206 90%-A/10%-B 0.109 0.1250.218 0.250 80%-A/20%-B 0.112 0.146 0.224 0.292 C 0.088 0.127 0.1760.254 95%-C/5%-B 0.073 0.113 0.146 0.226 90%-C/10%-B 0.085 0.128 0.1700.156 80%-C/20%-B 0.091 0.130 0.182 0.260

Without nucleation, adding 20 wt % of polymer B to polymer A produced afilm with increased permeability. With nucleation, permeabilitydecreases at both the low and maximum frost line heights. Thereforenucleation is successful in a multimodal HDPE blend at reducingpermeability, which creates a novel result. At low FLH, the nucleatedblend matches the permeability of polymer A. At maximum FLH, thenucleated blend provides the lowest permeability of all films studied.At both low and high frost line heights, adding 5% of polymer B topolymer A provided more improvement in barrier than does nucleationalone, which also is a novel result.

Nucleation also benefits the film optical properties when FLH ismaximized. Both polymer A and the unnucleated blend of polymer B andpolymer A have considerably more haze and less gloss than the nucleatedblend of polymer C and polymer B as shown in Table 4.

TABLE 4 Optical Properties Outside Gloss (45°) Haze (%) @ Low @ Max. @Low @ Max. Material FLH FLH FLH FLH A 25.6 13.6 32.7 53.6 95%-A/5%-B24.3 13.5 38.6 55.2 90%-A/10%-B 23.9 14.8 36.0 51.9 80%-A/20%-B 25.910.8 34.3 56.8 C 30.6 24.4 27.6 32.8 95%-C/5%-B 30.2 23.6 29.2 33.090%-C/10%-B 28.8 25.3 29.7 32.3 80%-C/20%-B 26.8 19.1 31.7 39.9

In addition, as shown in Table 5, the use of the nucleator reduces tearproperties in both the machine direction (MD) and the transversedirection (TD). The addition of 20 wt % of polymer B, however,compensates for this loss in tear resistance with the nucleated blendsmatching the results of the polymer A sample.

TABLE 5 Tear Properties of the Sample Films MD Tear TD Tear @ Low @ Max.@ Low @ Max. Material FLH FLH FLH FLH A 51.1 48.4 97.2 88.0 80%-A/20%-B44.7 71.7 99.2 74.4 C 36.0 37.2 57.6 46.4 80%-C/20%-B 41.4 45.2 104.484.8

The results of these experiments show that a polyethylene nucleator iseffective in a multimodal blend. The nucleated multimodal blends showedsignificant improvement in barrier properties over the unnucleatedversions, especially at higher frost line conditions. The nucleatedmultimodal blends also showed lower haze and higher gloss than theunnucleated blends when the frost line height is maximized. The blend ofpolymer A with 5 wt % of polymer B provided significant improvement inbarrier properties. According to FIG. 2, at both low and high frost lineheights, adding 5 wt % of polymer B to polymer A provided moreimprovement in barrier than by nucleation alone.

Example 3

Typically HDPE high barrier films (e.g., cereal liners) are composed ofat least three layers of coex blown films with an A/B/C structure (ausual layer distribution could be 45/45/10 or 40/40/20), where the Alayer (outer layer) is a high barrier HDPE, the B layer (core layer)could be a “lower cost” HDPE and the C layer (inside layer) is thesealing layer (usually EVA, LDPE or other special copolymers forpealability). Overall these films can have very good barrier propertiesand high stiffness; however, low tear strength and the relatively highcost (due to higher cost high barrier HDPE) are typical challenges.

In general, running a high-stalk film can help on the tear strength andbarrier (higher frost line height) sides; however, typical structurescannot be run in high-stalk mode. Even if a standard HMW-HDPE is used inthe core layer, the overall structure may not be stable enough to be runin high stalk mode in commercial lines/rates. Additionally, the WVTR ofstandard HMW-HDPE is relatively high and therefore is usually notconsidered an option for these applications. Nucleated polymers of thepresent disclosure may address these challenges by improving bubblestability, enabling the running at a higher frost line height, as wellas improved barrier properties of the HMW-HDPE.

TABLE 6 Target MI2 Target Density Grade [g/10 min] [g/cc] Comments BDM110-03 2 0.958 Developmental HDPE high barrier grade HL535 0.35 0.955Broad MWD HDPE M2710EP 0.9 0.927 Metallocene MDPE 2285 0.08 0.950Standard HMW-HDPE N11031 0.08 0.950 HMW-HDPE for ultra-thin films(2285 + 1,500 ppm HPN-20E nucleator)

Blown film samples comparing a typical MMW-HDPE structure, a film basedon a standard HMW-HDPE and a film using the ultra-thin HMW (N11031) wereproduced on a Davis Standard mini-coex line. Table 7 shows details ofthe structures evaluated.

TABLE 7 ID Structure MMW A/B/C (40/40/20) A = BDM1 10-03, B = HL535, C =M2710EP 2 mil, 2.5:1 BUR HMW A/B/C (40/40/20) A = BDM1 10-03, B = 2285,C = M2710EP 2 mil, ~4:1 BUR, high stalk Ultra-thin HMW A/B/C (40/40/20)A = BDM1 10-03, B = N11031, C = M2710EP 2 mil, ~4:1 BUR, high stalk

WVTR, falling dart impact resistance, tear strength and secant modulusproperties were evaluated for all the films.

Table 8 shows the WVTR, stiffness (secant modulus), impact (dart) andtear strength testing results. FIG. 5 presents a relative comparison ofthe three films under study. In general, the HMW structures compare wellwith the typical MMW film WVTR is at least equivalent or even slightlybetter for the ultra-thin HMW based film. Also, the dart strength forthe ultra-thin HMW based film is significantly higher. Moreover, asexpected, the HMW films show an increase in MD tear strength. On thestiffness side, the secant modulus of the film using the ultra-thinHMW-HDPE is comparable to the MMW film suggesting thatfilling/conversion should be similar

TABLE 8 Ultra-thin MMW HMW HMW Normalized WVTR 0.42 0.41 0.39 [g/100in²/day/mil] Dart [g] 56.9 60.0 98.2 1% Secant Modulus, MD [psi] 111,59976,225 111,466 1% Secant Modulus, TD [psi] 151,681 134,486 136,949 MDTear [g] 39 50 45 TD Tear [g] 283 227 245

As used herein, the term “homopolymer” refers to a polymer resultingfrom polymerization of a single monomer species.

As used herein, the term “co-polymer,” also known as a “heteropolymer,”is a polymer resulting from polymerization of two or more monomerspecies.

As used herein, the term “unimodal” refers to one discrete molecularweight distribution.

As used herein, the term “bimodal” refers to a mixture of two discretemolecular weight distributions.

As used herein, the term “multimodal” refers to a mixture of three ormore discrete molecular weight distributions.

As used herein, the term “multimodal films” refers to films having amixture of three or more discrete molecular weight distributions.

As used herein, the term “nucleating agent” refers to an agent, oradditive, that changes the crystallization behavior of a polymer as thepolymer melt is cooled.

As used herein, the term “frost line height” refers to the distance froma die face to where solidification occurs, or the point beyond a dieface where the temperature of the molten plastic falls below thesoftening point and the diameter of the extruded plastic bubblestabilizes.

As used herein the term “low frost line height” refers to operatinghaving a frost line height of less than 3 die diameters in height. Thisis sometimes referred to in the art as “running in the pocket” orrunning with “no neck”.

Use of the term “optionally” with respect to any element of a claim isintended to mean that the subject element is required, or alternatively,is not required. Both alternatives are intended to be within the scopeof the claim. Use of broader terms such as comprises, includes, having,etc. should be understood to provide support for narrower terms such asconsisting of, consisting essentially of, comprised substantially of,etc.

The various embodiments of the present disclosure can be joined incombination with other embodiments of the disclosure and the listedembodiments herein are not meant to limit the disclosure. Allcombinations of embodiments of the disclosure are enabled, even if notgiven in a particular example herein.

The foregoing outlines features of several embodiments so that a personof ordinary skill in the art may better understand the aspects of thepresent disclosure. Such features may be replaced by any one of numerousequivalent alternatives, only some of which are disclosed herein. One ofordinary skill in the art should appreciate that they may readily usethe present disclosure as a basis for designing or modifying otherprocesses and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein. Oneof ordinary skill in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions andalterations herein without departing from the spirit and scope of thepresent disclosure.

Where numerical ranges or limitations are expressly stated, such expressranges or limitations should be understood to include iterative rangesor limitations of like magnitude falling within the expressly statedranges or limitations (e.g., from about 1 to about 10 includes, 2, 3, 4,etc.; greater than 0.10 includes 0.11, 0.12, 0.13, etc.).

While the foregoing is directed to embodiments, versions and examples ofthe present disclosure, which are included to enable a person ofordinary skill in the art to make and use the disclosures when theinformation in this patent is combined with available information andtechnology, the disclosure is not limited to only these particularembodiments, versions and examples. Also, it is within the scope of thisdisclosure that the aspects and embodiments disclosed herein are usableand combinable with every other embodiment and/or aspect disclosedherein, and consequently, this disclosure is enabling for any and allcombinations of the embodiments and/or aspects disclosed herein. Otherand further embodiments, versions and examples of the disclosure may bedevised without departing from the basic scope thereof and the scopethereof is determined by the claims that follow.

What is claimed is:
 1. A composition comprising: a first polyethylenecomponent; a second bimodal or multimodal polyethylene component,wherein the first polyethylene component has a density ranging from0.880 g/cm³ to 0.940 g/cm³, wherein the second polyethylene componenthas a density ranging from 0.880 g/cm³ to 0.940 g/cm³, or wherein thefirst polyethylene component and the second polyethylene component havedensities ranging from 0.880 g/cm³ to 0.940 g/cm³; and a polyethylenecompatible nucleating agent.
 2. The composition of claim 1, wherein thefirst polyethylene component has a density ranging from 0.880 g/cm³ to0.940 g/cm³, and wherein the second bimodal or multimodal polyethylenecomponent is a high density polyethylene having a density ranging from0.950 to 0.970 g/cm³.
 3. The composition of claim 1, wherein the secondbimodal or multimodal polyethylene component has a density ranging from0.880 g/cm³ to 0.940 g/cm³, and wherein the first polyethylene componentis a high density polyethylene having a density ranging from 0.950 to0.970 g/cm³.
 4. The composition of claim 1, wherein the firstpolyethylene component and the second bimodal or multimodal polyethylenecomponent have densities ranging from 0.880 g/cm³ to 0.940 g/cm³.
 5. Thecomposition of claim 1, wherein the first polyethylene component ispresent in amounts ranging from 75 to 85 wt % based on a total weight ofthe composition.
 6. The composition of claim 1, wherein at max frostline height, a 2 mil film of the composition comprises a water vaportransmission rate (WVTR) of less than 0.250 g/100 in²/day, wherein theWVTR is measured at 100° F. in accordance with ASTM test method E96/66.7. The composition of claim 1, wherein a two mil film of the firstpolyethylene component exhibits an Elmendorf Tear strength, measuredusing the ASTM test method D 1922, in the machine direction ranging from10 to 50 g, and in the transverse direction ranging from 200 to 600 g.8. The composition of claim 1, wherein a two mil film of the secondpolyethylene component exhibits an Elmendorf Tear strength, measuredusing the ASTM test method D 1922, in the machine direction ranging from1 to 30 g, and in the transverse direction ranging from 100 to 10000 g.9. The composition of claim 1, wherein a two mil film of the firstpolyethylene component exhibits a tensile strength at yield, measuredusing the ASTM test method D 882A at 20 in/min, ranging from 1000 to6000 psi in the machine direction, and ranging from 1000 to 6000 psi inthe transverse direction.
 10. The composition of claim 1, wherein a twomil film of the first polyethylene component exhibits a tensile strengthat yield, measured using the ASTM test method D 882A at 20 in/min,ranging from 1000 to 6000 psi in the machine direction, and ranging from1000 to 4000 psi in the transvers direction.
 11. The composition ofclaim 1, wherein a two mil film of the second polyethylene componentexhibits a tensile strength at break ranging from 5000 to 10000 psi inthe machine direction, and ranging from 2000 to 5000 psi in thetransverse direction.
 12. The composition of claim 1, wherein a two milfilm of the second polyethylene component exhibits a tensile strength atbreak ranging from 5000 to 10000 psi in the machine direction, andranging from 1000 to 4000 psi in the transverse direction.
 13. Thecomposition of claim 1, wherein a two mil film of the first polyethylenecomponent exhibits an elongation at break in both the machine directionand transvers direction, measured using ASTM test method D 882A at 20in/min, ranging from 100 to 1000%.
 14. The composition of claim 1,wherein a two mil film of the second polyethylene component exhibits anelongation at break, measured using ASTM test method D 882A at 20in/min, ranging from 100 to 500% in the machine direction, and less than100% in the transverse direction.
 15. The composition of claim 1,wherein a two mil film of the first polyethylene component exhibits asecant modulus at 1% strain, measured using ASTM test method D 882A at20 in/min, in the machine direction ranging from 50 to 200 kpsi, and inthe transvers direction ranging from 50 to 200 kpsi.
 16. The compositionof claim 1, wherein a two mil film of the second polyethylene componentexhibits a secant modulus at 1% strain, measured using ASTM test methodD 882A at 20 in/min, in the machine direction ranging from 50 to 250kpsi, and in the transvers direction ranging from 100 to 300 kpsi. 17.The composition of claim 1, wherein a two mil film of the firstpolyethylene component exhibits a secant modulus at 2% strain, measuredusing ASTM test method D 882A at 1 in/min, in the machine directionranging from 50 to 200 kpsi, and in the transverse direction rangingfrom 50 to 200 kpsi.
 18. The composition of claim 1, wherein the secondpolyethylene component exhibits a dart impact, measured using ASTM testmethod D 1709A, of less than 100 g.
 19. A blown film made from acomposition comprising: a first polyethylene component; a second bimodalor multimodal polyethylene component, wherein the first polyethylenecomponent has a density ranging from 0.880 g/cm³ to 0.940 g/cm³, whereinthe second polyethylene component has a density ranging from 0.880 g/cm³to 0.940 g/cm³, or wherein the first polyethylene component and thesecond polyethylene component have densities ranging from 0.880 g/cm³ to0.940 g/cm³; and a polyethylene compatible nucleating agent.
 20. Amethod of making a composition comprising: combining a firstpolyethylene component, a second bimodal or multimodal polyethylenecomponent, and a polyethylene compatible nucleating agent, to form amultimodal resin; wherein the first polyethylene component has a densityranging from 0.880 g/cm³ to 0.940 g/cm³, wherein the second polyethylenecomponent has a density ranging from 0.880 g/cm³ to 0.940 g/cm³, orwherein the first polyethylene component and the second polyethylenecomponent have densities ranging from 0.880 g/cm³ to 0.940 g/cm³. 21.The method of claim 20, wherein the first polyethylene component or thesecond polyethylene component is a high density polyethylene having adensity ranging from 0.950 to 0.970 g/cm³.
 22. The article of claim 19,wherein the first polyethylene component or the second polyethylenecomponent is a high density polyethylene having a density ranging from0.950 to 0.970 g/cm³.
 23. The composition of claim 1, wherein thepolyethylene compatible nucleating agent comprises a carboxylic acidsalt, phosphate, metallic-silicate hydrate, sorbitol acetal, orcombinations thereof.
 24. The composition of claim 1, wherein thecomposition comprises from 75 to 99 weight percent of the firstpolyethylene component based on a total weight of the composition,wherein the first polyethylene component has a density ranging from0.880 g/cm³ to 0.940 g/cm³, and wherein the second bimodal or multimodalpolyethylene component has a density ranging from 0.950 to 0.970 g/cm³and a melt flow index of from 0.1 to 5.0 g/10 min. as measured inaccordance with ASTM D 1238 at 190° C. and a load of 2.16 kg.
 25. Thecomposition of claim 1, wherein the second bimodal or multimodalpolyethylene component comprises a polyethylene homopolymer and has adensity ranging from 0.880 g/cm³ to 0.940 g/cm³, and wherein the firstpolyethylene component is a high density polyethylene having a densityranging from 0.950 to 0.970 g/cm³ and a melt flow index of from 0.1 to5.0 g/10 min. as measured in accordance with ASTM D 1238 at 190° C. anda load of 2.16 kg.
 26. The composition of claim 1, wherein thecomposition comprises from 75 to 99 weight percent of the firstpolyethylene component based on a total weight of the composition,wherein the first polyethylene component has a density ranging from0.880 g/cm³ to 0.925 g/cm³ and the second bimodal or multimodalpolyethylene component has a density ranging from 0.880 g/cm³ to 0.940g/cm³.
 27. The composition of claim 1, wherein the second polyethylenecomponent is bimodal.